#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
using namespace std;
using ll=long long;
const int N=1e6+10;


int main() {

    ll x;
    cin>>x;
    long double t =sqrt(x);
    ll a;
    if(fabs(t-ceil(t))<fabs(t-floor(t)))
    {
        a=ceil(t);
    }
    else{
        a=floor(t);
    }
    cout<<a*a<<endl;
    return 0;
}
